From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
The torture_shuffle() function forces each CPU in turn to go idle
periodically in order to check for problems interacting with per-CPU
variables and with dyntick-idle mode. Because this sort of debugging
is not specific to RCU, this commit abstracts that functionality.
This in turn requires abstracting some additional infrastructure.
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
---
include/linux/torture.h | 5 ++
kernel/rcu/rcutorture.c | 124 +++++----------------------------------
kernel/torture.c | 151 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 171 insertions(+), 109 deletions(-)
diff --git a/include/linux/torture.h b/include/linux/torture.h
index 9b6a4834de8f..712a355cd817 100644
--- a/include/linux/torture.h
+++ b/include/linux/torture.h
@@ -69,6 +69,11 @@ struct torture_random_state {
#define DEFINE_TORTURE_RANDOM(name) struct torture_random_state name = { 0, 0 }
unsigned long torture_random(struct torture_random_state *trsp);
+/* Task shuffler, which causes CPUs to occasionally go idle. */
+void torture_shuffle_task_register(struct task_struct *tp);
+int torture_shuffle_init(long shuffint);
+void torture_shuffle_cleanup(void);
+
/* Shutdown task absorption, for when the tasks cannot safely be killed. */
void torture_shutdown_absorb(const char *title);
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 49cdeeaaa54b..7b56da0b8cfe 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -105,7 +105,6 @@ static struct task_struct *writer_task;
static struct task_struct **fakewriter_tasks;
static struct task_struct **reader_tasks;
static struct task_struct *stats_task;
-static struct task_struct *shuffler_task;
static struct task_struct *stutter_task;
static struct task_struct *fqs_task;
static struct task_struct *boost_tasks[NR_CPUS];
@@ -160,7 +159,6 @@ static int max_online;
static long n_barrier_attempts;
static long n_barrier_successes;
static struct list_head rcu_torture_removed;
-static cpumask_var_t shuffle_tmp_mask;
static int stutter_pause_test;
@@ -1079,90 +1077,6 @@ rcu_torture_stats(void *arg)
return 0;
}
-static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
-
-/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special
case
- * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
- */
-static void rcu_torture_shuffle_tasks(void)
-{
- int i;
-
- cpumask_setall(shuffle_tmp_mask);
- get_online_cpus();
-
- /* No point in shuffling if there is only one online CPU (ex: UP) */
- if (num_online_cpus() == 1) {
- put_online_cpus();
- return;
- }
-
- if (rcu_idle_cpu != -1)
- cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
-
- set_cpus_allowed_ptr(current, shuffle_tmp_mask);
-
- if (reader_tasks) {
- for (i = 0; i < nrealreaders; i++)
- if (reader_tasks[i])
- set_cpus_allowed_ptr(reader_tasks[i],
- shuffle_tmp_mask);
- }
- if (fakewriter_tasks) {
- for (i = 0; i < nfakewriters; i++)
- if (fakewriter_tasks[i])
- set_cpus_allowed_ptr(fakewriter_tasks[i],
- shuffle_tmp_mask);
- }
- if (writer_task)
- set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
- if (stats_task)
- set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
- if (stutter_task)
- set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
- if (fqs_task)
- set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
- if (shutdown_task)
- set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
-#ifdef CONFIG_HOTPLUG_CPU
- if (onoff_task)
- set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
-#endif /* #ifdef CONFIG_HOTPLUG_CPU */
- if (stall_task)
- set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
- if (barrier_cbs_tasks)
- for (i = 0; i < n_barrier_cbs; i++)
- if (barrier_cbs_tasks[i])
- set_cpus_allowed_ptr(barrier_cbs_tasks[i],
- shuffle_tmp_mask);
- if (barrier_task)
- set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
-
- if (rcu_idle_cpu == -1)
- rcu_idle_cpu = num_online_cpus() - 1;
- else
- rcu_idle_cpu--;
-
- put_online_cpus();
-}
-
-/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
- * system to become idle at a time and cut off its timer ticks. This is meant
- * to test the support for such tickless idle CPU in RCU.
- */
-static int
-rcu_torture_shuffle(void *arg)
-{
- VERBOSE_TOROUT_STRING("rcu_torture_shuffle task started");
- do {
- schedule_timeout_interruptible(shuffle_interval * HZ);
- rcu_torture_shuffle_tasks();
- torture_shutdown_absorb("rcu_torture_shuffle");
- } while (!kthread_should_stop());
- VERBOSE_TOROUT_STRING("rcu_torture_shuffle task stopping");
- return 0;
-}
-
/* Cause the rcutorture test to "stutter", starting and stopping all
* threads periodically.
*/
@@ -1396,6 +1310,7 @@ rcu_torture_onoff_init(void)
onoff_task = NULL;
return ret;
}
+ torture_shuffle_task_register(onoff_task);
return 0;
}
@@ -1467,6 +1382,7 @@ static int __init rcu_torture_stall_init(void)
stall_task = NULL;
return ret;
}
+ torture_shuffle_task_register(stall_task);
return 0;
}
@@ -1593,6 +1509,7 @@ static int rcu_torture_barrier_init(void)
barrier_cbs_tasks[i] = NULL;
return ret;
}
+ torture_shuffle_task_register(barrier_cbs_tasks[i]);
}
barrier_task = kthread_run(rcu_torture_barrier, NULL,
"rcu_torture_barrier");
@@ -1601,6 +1518,7 @@ static int rcu_torture_barrier_init(void)
VERBOSE_TOROUT_ERRSTRING("Failed to create
rcu_torture_barrier");
barrier_task = NULL;
}
+ torture_shuffle_task_register(barrier_task);
return 0;
}
@@ -1673,6 +1591,8 @@ rcu_torture_cleanup(void)
fullstop = FULLSTOP_RMMOD;
mutex_unlock(&fullstop_mutex);
unregister_reboot_notifier(&rcutorture_shutdown_nb);
+
+ torture_shuffle_cleanup(); /* Must be first task cleaned up. */
rcu_torture_barrier_cleanup();
rcu_torture_stall_cleanup();
if (stutter_task) {
@@ -1680,12 +1600,6 @@ rcu_torture_cleanup(void)
kthread_stop(stutter_task);
}
stutter_task = NULL;
- if (shuffler_task) {
- VERBOSE_TOROUT_STRING("Stopping rcu_torture_shuffle task");
- kthread_stop(shuffler_task);
- free_cpumask_var(shuffle_tmp_mask);
- }
- shuffler_task = NULL;
if (writer_task) {
VERBOSE_TOROUT_STRING("Stopping rcu_torture_writer task");
@@ -1903,6 +1817,7 @@ rcu_torture_init(void)
writer_task = NULL;
goto unwind;
}
+ torture_shuffle_task_register(writer_task);
wake_up_process(writer_task);
fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
GFP_KERNEL);
@@ -1921,6 +1836,7 @@ rcu_torture_init(void)
fakewriter_tasks[i] = NULL;
goto unwind;
}
+ torture_shuffle_task_register(fakewriter_tasks[i]);
}
reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
GFP_KERNEL);
@@ -1939,6 +1855,7 @@ rcu_torture_init(void)
reader_tasks[i] = NULL;
goto unwind;
}
+ torture_shuffle_task_register(reader_tasks[i]);
}
if (stat_interval > 0) {
VERBOSE_TOROUT_STRING("Creating rcu_torture_stats task");
@@ -1950,26 +1867,12 @@ rcu_torture_init(void)
stats_task = NULL;
goto unwind;
}
+ torture_shuffle_task_register(stats_task);
}
if (test_no_idle_hz) {
- rcu_idle_cpu = num_online_cpus() - 1;
-
- if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
- firsterr = -ENOMEM;
- VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
+ firsterr = torture_shuffle_init(shuffle_interval * HZ);
+ if (firsterr)
goto unwind;
- }
-
- /* Create the shuffler thread */
- shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
- "rcu_torture_shuffle");
- if (IS_ERR(shuffler_task)) {
- free_cpumask_var(shuffle_tmp_mask);
- firsterr = PTR_ERR(shuffler_task);
- VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler");
- shuffler_task = NULL;
- goto unwind;
- }
}
if (stutter < 0)
stutter = 0;
@@ -1983,6 +1886,7 @@ rcu_torture_init(void)
stutter_task = NULL;
goto unwind;
}
+ torture_shuffle_task_register(stutter_task);
}
if (fqs_duration < 0)
fqs_duration = 0;
@@ -1996,6 +1900,7 @@ rcu_torture_init(void)
fqs_task = NULL;
goto unwind;
}
+ torture_shuffle_task_register(fqs_task);
}
if (test_boost_interval < 1)
test_boost_interval = 1;
@@ -2026,6 +1931,7 @@ rcu_torture_init(void)
shutdown_task = NULL;
goto unwind;
}
+ torture_shuffle_task_register(shutdown_task);
wake_up_process(shutdown_task);
}
i = rcu_torture_onoff_init();
diff --git a/kernel/torture.c b/kernel/torture.c
index f05042036ae8..26058f20ee83 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -76,6 +76,157 @@ torture_random(struct torture_random_state *trsp)
EXPORT_SYMBOL_GPL(torture_random);
/*
+ * Variables for shuffling. The idea is to ensure that each CPU stays
+ * idle for an extended period to test interactions with dyntick idle,
+ * as well as interactions with any per-CPU varibles.
+ */
+struct shuffle_task {
+ struct list_head st_l;
+ struct task_struct *st_t;
+};
+
+static long shuffle_interval; /* In jiffies. */
+static struct task_struct *shuffler_task;
+static cpumask_var_t shuffle_tmp_mask;
+static int shuffle_idle_cpu; /* Force all torture tasks off this CPU */
+static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
+static DEFINE_MUTEX(shuffle_task_mutex);
+
+/*
+ * Register a task to be shuffled. If there is no memory, just splat
+ * and don't bother registering.
+ */
+void torture_shuffle_task_register(struct task_struct *tp)
+{
+ struct shuffle_task *stp;
+
+ if (WARN_ON_ONCE(tp == NULL))
+ return;
+ stp = kmalloc(sizeof(*stp), GFP_KERNEL);
+ if (WARN_ON_ONCE(stp == NULL))
+ return;
+ stp->st_t = tp;
+ mutex_lock(&shuffle_task_mutex);
+ list_add(&stp->st_l, &shuffle_task_list);
+ mutex_unlock(&shuffle_task_mutex);
+}
+EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
+
+/*
+ * Unregister all tasks, for example, at the end of the torture run.
+ */
+static void torture_shuffle_task_unregister_all(void)
+{
+ struct shuffle_task *stp;
+ struct shuffle_task *p;
+
+ mutex_lock(&shuffle_task_mutex);
+ list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
+ list_del(&stp->st_l);
+ kfree(stp);
+ }
+ mutex_unlock(&shuffle_task_mutex);
+}
+
+/* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
+ * A special case is when shuffle_idle_cpu = -1, in which case we allow
+ * the tasks to run on all CPUs.
+ */
+static void torture_shuffle_tasks(void)
+{
+ struct shuffle_task *stp;
+
+ cpumask_setall(shuffle_tmp_mask);
+ get_online_cpus();
+
+ /* No point in shuffling if there is only one online CPU (ex: UP) */
+ if (num_online_cpus() == 1) {
+ put_online_cpus();
+ return;
+ }
+
+ /* Advance to the next CPU. Upon overflow, don't idle any CPUs. */
+ shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
+ if (shuffle_idle_cpu >= nr_cpu_ids)
+ shuffle_idle_cpu = -1;
+ if (shuffle_idle_cpu != -1) {
+ cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
+ if (cpumask_empty(shuffle_tmp_mask)) {
+ put_online_cpus();
+ return;
+ }
+ }
+
+ mutex_lock(&shuffle_task_mutex);
+ list_for_each_entry(stp, &shuffle_task_list, st_l)
+ set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
+ mutex_unlock(&shuffle_task_mutex);
+
+ put_online_cpus();
+}
+
+/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
+ * system to become idle at a time and cut off its timer ticks. This is meant
+ * to test the support for such tickless idle CPU in RCU.
+ */
+static int torture_shuffle(void *arg)
+{
+ VERBOSE_TOROUT_STRING("torture_shuffle task started");
+ do {
+ schedule_timeout_interruptible(shuffle_interval);
+ torture_shuffle_tasks();
+ torture_shutdown_absorb("torture_shuffle");
+ } while (!torture_must_stop());
+ VERBOSE_TOROUT_STRING("torture_shuffle task stopping");
+ return 0;
+}
+
+/*
+ * Start the shuffler, with shuffint in jiffies.
+ */
+int torture_shuffle_init(long shuffint)
+{
+ int ret;
+
+ shuffle_interval = shuffint;
+
+ shuffle_idle_cpu = -1;
+
+ if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
+ VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
+ return -ENOMEM;
+ }
+
+ /* Create the shuffler thread */
+ shuffler_task = kthread_run(torture_shuffle, NULL, "torture_shuffle");
+ if (IS_ERR(shuffler_task)) {
+ ret = PTR_ERR(shuffler_task);
+ free_cpumask_var(shuffle_tmp_mask);
+ VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler");
+ shuffler_task = NULL;
+ return ret;
+ }
+ torture_shuffle_task_register(shuffler_task);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(torture_shuffle_init);
+
+/*
+ * Stop the shuffling.
+ */
+void torture_shuffle_cleanup(void)
+{
+ torture_shuffle_task_unregister_all();
+ if (shuffler_task) {
+ VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
+ kthread_stop(shuffler_task);
+ free_cpumask_var(shuffle_tmp_mask);
+ }
+ shuffler_task = NULL;
+}
+EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
+
+/*
* Absorb kthreads into a kernel function that won't return, so that
* they won't ever access module text or data again.
*/
--
1.8.1.5
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